linux-kernel - [PATCH -next v6 08/10] entry: Add arch_ptrace_report_syscall

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Message-ID: <20250916082611.2972008-9-ruanjinjie@huawei.com>
Date: Tue, 16 Sep 2025 16:26:09 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: <catalin.marinas@....com>, <will@...nel.org>, <oleg@...hat.com>,
	<tglx@...utronix.de>, <peterz@...radead.org>, <luto@...nel.org>,
	<kees@...nel.org>, <wad@...omium.org>, <charlie@...osinc.com>,
	<macro@...am.me.uk>, <deller@....de>, <akpm@...ux-foundation.org>,
	<ldv@...ace.io>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
CC: <ruanjinjie@...wei.com>
Subject: [PATCH -next v6 08/10] entry: Add arch_ptrace_report_syscall_entry/exit()

Differ from generic entry, due to historical reasons, ARM64 need to
save/restore during syscall entry/exit because ARM64 use a scratch
register (ip(r12) on AArch32, x7 on AArch64) to denote syscall entry/exit.

In preparation for moving arm64 over to the generic entry code,
add arch_ptrace_report_syscall_entry/exit() as the default
ptrace_report_syscall_entry/exit() implementation. This allows
arm64 to implement the architecture specific version.

Suggested-by: Mark Rutland <mark.rutland@....com>
Suggested-by: Kevin Brodsky <kevin.brodsky@....com>
Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
 kernel/entry/syscall-common.c | 43 +++++++++++++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 2 deletions(-)

diff --git a/kernel/entry/syscall-common.c b/kernel/entry/syscall-common.c
index 66e6ba7fa80c..27310e611567 100644
--- a/kernel/entry/syscall-common.c
+++ b/kernel/entry/syscall-common.c
@@ -17,6 +17,25 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
 	}
 }
 
+/**
+ * arch_ptrace_report_syscall_entry - Architecture specific
+ *				      ptrace_report_syscall_entry().
+ *
+ * Invoked from syscall_trace_enter() to wrap ptrace_report_syscall_entry().
+ * Defaults to ptrace_report_syscall_entry.
+ *
+ * The main purpose is to support arch-specific ptrace_report_syscall_entry()
+ * implementation.
+ */
+static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs);
+
+#ifndef arch_ptrace_report_syscall_entry
+static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs)
+{
+	return ptrace_report_syscall_entry(regs);
+}
+#endif
+
 long syscall_trace_enter(struct pt_regs *regs, long syscall,
 				unsigned long work)
 {
@@ -34,7 +53,7 @@ long syscall_trace_enter(struct pt_regs *regs, long syscall,
 
 	/* Handle ptrace */
 	if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) {
-		ret = ptrace_report_syscall_entry(regs);
+		ret = arch_ptrace_report_syscall_entry(regs);
 		if (ret || (work & SYSCALL_WORK_SYSCALL_EMU))
 			return -1L;
 	}
@@ -84,6 +103,26 @@ static inline bool report_single_step(unsigned long work)
 	return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP;
 }
 
+/**
+ * arch_ptrace_report_syscall_exit - Architecture specific
+ *				     ptrace_report_syscall_exit.
+ *
+ * Invoked from syscall_exit_work() to wrap ptrace_report_syscall_exit().
+ *
+ * The main purpose is to support arch-specific ptrace_report_syscall_exit
+ * implementation.
+ */
+static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
+							    int step);
+
+#ifndef arch_ptrace_report_syscall_exit
+static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs,
+							    int step)
+{
+	ptrace_report_syscall_exit(regs, step);
+}
+#endif
+
 void syscall_exit_work(struct pt_regs *regs, unsigned long work)
 {
 	bool step;
@@ -108,5 +147,5 @@ void syscall_exit_work(struct pt_regs *regs, unsigned long work)
 
 	step = report_single_step(work);
 	if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
-		ptrace_report_syscall_exit(regs, step);
+		arch_ptrace_report_syscall_exit(regs, step);
 }
-- 
2.34.1